NOAA Scientist Finds Clue to Predicting Solar Flares

NOAA News Release

2010 January 19

For decades, experts have searched for signs in the sun that could lead to more
accurate forecasts of solar flares — powerful blasts of energy that can
supercharge Earth’s upper atmosphere and disrupt satellites and the land-based
technologies on which modern societies depend. Now a scientist at NOAA’s Space
Weather Prediction Center and her colleagues have found a technique for
predicting solar flares two to three days in advance with unprecedented
accuracy.

The long-sought clue to prediction lies in changes in twisting magnetic fields
beneath the surface of the sun in the days leading up to a flare, according to
the authors. The findings will be published in Astrophysical Journal Letters
next month.

“For the first time, we can tell two to three days in advance when and where a
solar flare will occur and how large it will be,” said lead author Alysha
Reinard, a solar physicist at NOAA’s Space Weather Prediction Center and the
Cooperative Institute for Research in the Environmental Sciences, a partnership
between NOAA and the University of Colorado.

The new technique is already twice as accurate as current methods, according to
the authors, and that number is expected to improve as they refine their work
over the next few years. With this technique, reliable watches and warnings
should be possible before the next solar sunspot maximum, predicted to occur in
2013. Currently, forecasters see complex sunspot regions and issue alerts that
a large flare may erupt, but the when-and-where eludes them.

Solar flares are sudden bursts of energy and light from sunspots’ magnetic
fields. During a flare, photons travel at the speed of light in all directions
through space, arriving at Earth’s upper atmosphere—93 million miles from the
sun—in just eight minutes.

Almost instantly the photons can affect the high-orbiting satellites of the
Global Positioning System, or GPS, creating timing delays and skewing
positioning signals by as much as half a football field, risking high-precision
agriculture, oil drilling, military and airline operations, financial
transactions, navigation, disaster warnings, and other critical functions
relying on GPS accuracy.

“Two or three days lead time can make the difference between safeguarding the
advanced technologies we depend on every day for our livelihood and security,
and the catastrophic loss of these capabilities and trillions of dollars in
disrupted commerce,” said Thomas Bogdan, director of NOAA’s Space Weather
Prediction Center.

Reinard and NOAA intern Justin Henthorn of Ohio University pored over detailed
maps of more than 1,000 sunspot groups, called active regions. The maps were
constructed from solar sound-wave data from the National Science Foundation’s
Global Oscillation Network Group.

Reinard and Henthorn found the same pattern in region after region: magnetic
twisting that tightened to the breaking point, burst into a large flare, and
vanished. They established that the pattern could be used as a reliable tool for
predicting a solar flare.

“These recurring motions of the magnetic field, playing out unseen beneath the
solar surface, are the clue we’ve needed to know that a large flare is coming—and when,” said Reinard.

Rudi Komm and Frank Hill of the National Solar Observatory contributed to the
research.

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